A rail brace is used to stabilize and support a rail, preventing it from rolling over due to lateral loads applied to the rail head by passing trains. In applications such as switches, curves and similar areas where only one side of the rail is braced, it is crucial to provide a sufficiently strong and resilient rail brace to oppose the rollover and lateral forces applied by passing trains. However, it is also economically important to minimize the time and manpower required to install and maintain brace assemblies. Bolted brace assemblies, where the brace is bolted through the tie plate, are more costly and difficult to manufacture, install and maintain. Boltless versions, wherein the brace is retained by an inelastic or elastic fastener, may therefore be preferred.
U.S. Pat. No. 2,101,313 to Gillespie discloses a rail brace assembly having a brace mounted on the rail plate to support the toe of a spring wedge, pressing the wedge against the web and down onto the base of the rail. A pawl in the brace engages with the spring wedge to force the wedge laterally against the rail and to lock the wedge in place against the rail. The spring wedge is made of two pieces with their ends welded together but otherwise having a gap between them to provide shock absorption and resilience when the load of a passing train is applied.
U.S. Pat. No. 4,119,271 to Campbell discloses a rail brace that relies solely on an elongated elastic fastener to both hold down the rail base and to provide lateral support by extending to abut the underside of the rail head. Due to the shape and material from which the brace is made, the brace provides a certain degree of resilience under lateral forces.
U.S. Pat. No. 4,566,630 to Keiper, Jr. discloses a boltless, friction fit adjustable brace that includes a brace wedged against the rail between the lower side of the rail head and having a toe that extends over and past the upper side of the rail foot. A washer is held down over the brace toe by a spring clip supported on a stop block (also called a brace block or wedge block). The dimensions of the brace are tapered, allowing the brace to be tightly wedged between the rail and the stop block. Rollover and lateral forces from passing trains are resisted by the abutment of the brace and the stop block, and downward force of the spring clip on the toe of the brace.
U.S. Pat. No. 4,824,015 to Farrell et al. discloses a similar system, in which the washer is omitted and the spring clip appears to bear directly on an upper surface of the toe of a rail brace. Extending legs on the brace toe surround the spring clip retainer, ensuring that the brace does not move along the length of the rail. U.S. Pat. No. 5,104,041 to Remington discloses a similar arrangement, with the addition of a bearing insert between the brace toe and the toe of the spring clip, which seems to fulfill a similar function as a washer.
U.S. Pat. No. 4,770,342 to Farrell et al. discloses a rail brace system wherein the washer is replaced by an L-shaped cover plate, similar to the bearing insert of Remington but larger, inserted between the brace toe and the wedge block. Serrated surfaces and wedge-shaped faces ensure a very secure fit between the brace and the wedge block. However the spring clip exerts a downward force on the distal side of the cover block from the brace toe, rather than applying downward force directly over the toe. While the large cover plate may provide a very snug wedge between the brace toe and the wedge block, the downward force is quite removed from the brace and therefore might not provide sufficient force to restrain the rail.
U.S. Pat. No. 6,758,406 to Weaver discloses a rail brace assembly having a brace wedged against the rail between the lower side of the rail head and the upper side of the rail foot. The lower front surface of the brace includes a tongue, which interlocks with a groove in the wedge block. The brace tongue is angled, so it can be wedged between the rail and the wedge block to secure it along the rail web. The brace has an approximately central shoulder having a serrated upward-facing surface. A fastener plate sits on the serrated surface of the brace shoulder and is held down by a spring clip, which applies a downward force to the fastener plate and to the brace shoulder to hold the brace in position. Weaver's system may be more stable than that disclosed by Keiper, in that the downward force applied to the brace is somewhat more centralized and applied more into the body of the brace and the rail, and the interlocking of the brace and the wedge block may provide more stability than a simple abutment.
U.S. Pat. Nos. 8,313,041, 7,641,128, 6,308,897 and 6,517,008 to Remington et al. and U.S. Pat. No. 6,971,610 to Hein each similarly disclose brace assemblies wherein the clip retainer is positioned to allow the spring clip to exert force on the central part of the brace. The assemblies also comprise the toe of the brace, or a wedging piece positioned at the toe of the brace, interlocking with the stop block.
The primary lateral force applied by these brace assemblies is supplied by the tapered faces of the brace and wedge blocks to force the brace against the rail web, the underside of the rail head and the top of the rail base. Additionally, each brace assembly applies a downward clamping force, provided by the toe of the spring clip and/or a wedge near the brace toe. However, in each case, the locking of the brace to the rail is controlled and applied solely by the force of the spring clip. During installation, if the applied loads exceed the toe load of the clip, the clip may not hold. The brace will then loosen, allowing the tie assembly to fall off.
In order to overcome this potential problem, brace assemblies have been developed that avoid the need for a spring clip entirely. For example, U.S. Pat. No. 6,568,601 to Maynard discloses a rail brace assembly where the brace is held by a wedge tightly fitted between the brace toe and a stop block. A second downward vertical force is supplied by the interaction of a set of ribs underneath the brace with a block welded to the base plate. Again, the primary forces are applied directly to the brace and the brace toe. Further, construction and installation of the brace assembly may be complicated by the need to locate and weld the block to the base plate, as well as to ensure that the ribs of the brace are interlocked with the block.
It is therefore an object of the invention to provide a rail brace assembly that addresses the foregoing deficiencies.
It is a further object of the invention to provide a rail brace assembly that clamps the brace mechanically using a wedge to maintain a constant load on the brace itself.
It is a further object of the invention to provide a brace assembly that is universal, able to be used with almost any rail section.
It is yet a further object of the invention to provide a brace assembly that comprises a resilient aspect, in order to better manage lateral loads applied by the wheels of passing trains.
These and other objects of the invention will be better understood by reference to the detailed description of the preferred embodiment which follows. Note that the objects referred to above are statements of what motivated the invention rather than promises. Not all of the objects are necessarily met by all embodiments of the invention described below or by the invention defined by each of the claims.